*{
    margin: 0;
    padding: 0;
}
#box1{
    height: 100vh;
    width: 100%;
    background-image: url(bj4.jpg);
    background-size: cover;
    display: table;
    background-attachment: fixed;
}
#box2{
    height: 100vh;
    width: 100%;
    background-image: url(bj1.jpg);
    background-size: cover;
    display: table;
    background-attachment: fixed;
}
#box3{
    height: 100vh;
    width: 100%;
    background-image: url(bj2.jpg);
    background-size: cover;
    display: table;
    background-attachment: fixed;
}
h1{
    font-size: 50px;
    color: white;
    margin: 0;
    text-align: center;
    display: table-cell;
    vertical-align: middle;
}

